I keep getting a an "Invalid Range" error on two very simple section curves I'm try to extrude. Please see the attached of what I'm try to accomplish. I don't know what I'm doing wrong. Any suggestion would be greatly appreciated.

That's a typical case of the swept shape function.
There are 2 important conditions :
- the curve section and the drive line need to intersect (there might be an other way but so far never worked otherwise for me)
- the origin of the curve sections need to be set correctly

Enclosed is a swept shape I made using the same idea than what you are trying to do. I draw only half of the shapes in order to create an intersection between the sections and the drive line. Then I used the Profil/Origin function to set the origin and the orientation of the 2 curve sections the same way (origins are on the intersection point with the drive line). You can draw your shape at this point and play with the different options available (make sure you set the vertical orientation perpendicular to the drive line). I used the coresponding option to match the corners of the first section to the corners of the second section, otherwise the shape is not continuous in this area).
Then use the Shape/Other surface function/Motif to create the complete shape by symetricality).

I attached a few snap shots also, I'm using a french TopSolid and not sure what the corresponding functions are really called. Let me know if you need more explanations.
Feel free to modify my top file if you wish to use it in your design also.